As the title suggests, chocolate is involved in the main story's obligatory train crash. Because of a water shortage, Sir Topham Hatt's motto is "Usefulness before cleanliness," but when Bon Bon Percy plows through a factory wall and ends up doused in dessert topping, he earns himself a washdown. The other 5 stories involve Bill and Ben, the buffer brothers; self-important Gordon and his rivalry with Salty; Petersam losing two whistles; and resolving the question of who gets to transport the mouse-fearing opera singer Allicia Botti. The stories deal with the frequent "Thomas" theme of how jealousies, petty fights, and rivalries keep trains from working together. The use of anthropomorphic vehicles somehow makes the message more subtle--and thus more palatable--than many other children's series. A music video sung by children lauding the virtues of small engines wraps up this 38-minute program. (Ages 3 to 7) --Kimberly Heinrichs